/**
 * Reporting API Client
 *
 * Client functions for the Executive Reporting module.
 * Communicates with the Go backend via Next.js API proxy at /api/sdk/v1/reporting/*
 */

import type {
  ExecutiveReport,
  ComplianceScoreResponse,
  Deadline,
  RiskOverview,
} from './types'

const BASE_URL = '/api/sdk/v1/reporting'

/**
 * Rekursive snake_case -> camelCase Konvertierung fuer API-Responses.
 * Das Go-Backend liefert snake_case JSON, der TypeScript-Client erwartet camelCase.
 */
function snakeToCamel(str: string): string {
  return str.replace(/_([a-z])/g, (_, letter) => letter.toUpperCase())
}

function transformKeys(obj: unknown): unknown {
  if (Array.isArray(obj)) {
    return obj.map(transformKeys)
  }
  if (obj !== null && typeof obj === 'object') {
    return Object.fromEntries(
      Object.entries(obj as Record<string, unknown>).map(([key, value]) => [
        snakeToCamel(key),
        transformKeys(value),
      ])
    )
  }
  return obj
}

async function apiFetch<T>(path: string): Promise<T> {
  const res = await fetch(`${BASE_URL}${path}`, {
    headers: {
      'Content-Type': 'application/json',
      'X-Tenant-ID': typeof window !== 'undefined'
        ? (localStorage.getItem('bp-tenant-id') || 'default')
        : 'default',
    },
  })

  if (!res.ok) {
    const error = await res.json().catch(() => ({ error: res.statusText }))
    throw new Error(error.error || `API Error: ${res.status}`)
  }

  const data = await res.json()
  return transformKeys(data) as T
}

/**
 * Vollstaendigen Executive Report abrufen
 * GET /sdk/v1/reporting/executive
 */
export async function getExecutiveReport(): Promise<ExecutiveReport> {
  return apiFetch<ExecutiveReport>('/executive')
}

/**
 * Nur den Compliance-Score abrufen (leichtgewichtig)
 * GET /sdk/v1/reporting/score
 */
export async function getComplianceScore(): Promise<ComplianceScoreResponse> {
  return apiFetch<ComplianceScoreResponse>('/score')
}

/**
 * Bevorstehende Fristen abrufen
 * GET /sdk/v1/reporting/deadlines
 */
export async function getUpcomingDeadlines(): Promise<{ deadlines: Deadline[]; total: number }> {
  return apiFetch<{ deadlines: Deadline[]; total: number }>('/deadlines')
}

/**
 * Risikouebersicht abrufen
 * GET /sdk/v1/reporting/risks
 */
export async function getRiskOverview(): Promise<RiskOverview> {
  return apiFetch<RiskOverview>('/risks')
}